Explanation

The correct phrase is keen on when expressing interest or enthusiasm.

“She is keen on learning new languages” is the grammatically correct construction.

Explanation

Third conditional uses had + past participle in the if-clause (If I had left earlier…).

It describes an unreal past situation with a missed result (…I would have caught the train).

Explanation

"Lucid" means expressed clearly; easy to understand.

Since "everyone understood immediately," the explanation must have been clear and easy to follow. 

Explanation

He devotes much of his time to planning for the future 

 وہ اپنا زیادہ تر وقت مستقبل کی منصوبہ بندی میں صرف کرتا ہے

Subject: "He"

Verb: "devotes"

The object of the verb: "Much of his time"

Gerund Phrase (acting as a noun): "Planning for the future"

Explanation

If she were free, she would talk to you 

 اگر وہ فارغ ہوتی تو آپ سے بات کرتی

Formula for second conditional: If + past simple, would/wouldn't + verb.